Noob question from a veteran SH player
 

I'm not sure how to tell how far I have progressed to accomplish my mission. I am trying to do the mission "Siege of Tobruk." I sunk one merchant . . . how can I tell if this has helped my progress? Where do I look to see how much more I must do to finish "The Siege of Tobruk?"

Click on the mission icon on the map. If you have sunk tonnage that is specific to the mission, the tonnage bar will have been filled in (white) proportion to the amount of ships or tonnage required to satisfy the mission.